I have noticed that the low coolant warning light doesn't turn on even when the level is obviously too low. It used to work fine months ago, and the bulb is working ok too, so I guess it might be a broken sensor, but I would like to check it before ordering a new one. Any ideas about how to diagnose? Thank you very much for your help!

 

It would help if you let us know what kind of car you have.

 

My fault, sorry! I have a V70, year 1997.